Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period

Research output: Contribution to journalArticle

Authors

Colleges, School and Institutes

External organisations

  • British Antarctic Survey
  • University of Cambridge

Abstract

Greenland ice cores provide excellent evidence of past abrupt climate changes. However, there is no universally accepted theory of how and why these Dansgaard–Oeschger (DO) events occur. Several mechanisms have been proposed to explain DO events, including sea ice, ice shelf buildup, ice sheets, atmospheric circulation, and meltwater changes. DO event temperature reconstructions depend on the stable water isotope (δ 18 O) and nitrogen isotope measurements from Greenland ice cores: interpretation of these measurements holds the key to understanding the nature of DO events. Here, we demonstrate the primary importance of sea ice as a control on Greenland ice core δ 18 O: 95% of the variability in δ 18 O in southern Greenland is explained by DO event sea ice changes. Our suite of DO events, simulated using a general circulation model, accurately captures the amplitude of δ 18 O enrichment during the abrupt DO event onsets. Simulated geographical variability is broadly consistent with available ice core evidence. We find an hitherto unknown sensitivity of the δ 18 O paleothermometer to the magnitude of DO event temperature increase: the change in δ 18 O per Kelvin temperature increase reduces with DO event amplitude. We show that this effect is controlled by precipitation seasonality.

Bibliographic note

Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period, Louise C. Sime, Peter O. Hopcroft, Rachael H. Rhodes, Proceedings of the National Academy of Sciences Feb 2019, 201807261; DOI: 10.1073/pnas.1807261116

Details

Original languageEnglish
Pages (from-to)4099-4104
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume116
Issue number10
Publication statusPublished - 13 Feb 2019

Keywords

  • abrupt warmings, climate change, Arctic, sea ice, paleoclimate